Rush Hour puzzle solver and generator

The Rush Hour puzzle game was invented by Nob Yoshigahara in the 1970s and made its way to the United States in the 1990s. There are vehicles of varying length in a parking lot, and you have to figure out how to get one of the cars out by shifting all the others inside a six-by-six grid. Michael Fogleman wrote a solver and generator for the game, resulting in a database of 1.5 million puzzles.